FIG. 1 is a simplified view of a conventional prior art inkjet cartridge. It comprises a moulded plastics cartridge body 10 containing one or more internal ink reservoirs. A printhead 12 is mounted in a recess 14 in the surface of the body 10. As is well known, a typical printhead 12 contains a large number of internal ink ejection elements which can be selectively actuated by printer circuitry via a flexible printed circuit 16 bonded to the surface of the cartridge body. Each time an ink ejection element is actuated, a drop of ink is ejected forcibly through a respective orifice 18 in the exposed (outer) surface of the printhead. The ink is supplied to the printhead via one or more ink supply slots in the underside of the printhead which are in fluid communication with the ink reservoirs) via respective apertures in the cartridge body 10.
The flexible printed circuit 16 is shown flat in FIG. 2 although in use it is usually bent around two sides of the cartridge body 10 as seen in FIG. 1. The view in FIG. 2 is of the underside of the flexible printed circuit, i.e. the surface bonded to the cartridge body 10 in FIG. 1. The underside of the flexible printed circuit 16 comprises a first set of electrical terminals 20 and a second set of electrical terminals 22. In the simplified diagrams of FIGS. 1 and 2 only eight terminals are shown in each set, but in practice there will many more, typically 20 terminals in each set. The terminals 20 of the first set are disposed along opposite edges of an aperture 24 in the flexible printed circuit 16, and each is in the form of a respective cantilevered metal beam (“flex beam”) which extends into the aperture 24. The terminals 22 of the second set extend through the thickness of the material of the flexible printed circuit to be accessible on the outside surface of the flexible printed circuit, as seen in FIG. 1. The flex beams 20 are selectively connected to the terminals 22 via conductive tracks 26 on the underside of the flexible printed circuit.
The conventional printhead 12 has two rows of edge contacts on its outer surface, i.e. on the same side of the printhead as the orifices 18, and in the assembled cartridge with the printhead 12 seated in the recess 14 each edge contact is electrically connected to a respective one of the flex beams 20 (for simplicity, the edge contacts and flex beams are not shown in FIG. 1). When the cartridge is inserted into a compatible printer, the electrical terminals 22 mate with corresponding electrical terminals of the printer circuitry, so that the latter can selectively actuate the ink ejection elements via the conductive tracks 26 and flex beams 20 in known manner.
The conventional inkjet cartridge described above has certain disadvantages. Since the connections between the edge contacts of the printhead and the flex beams 20 are made at the outer surface of the printhead, the print head has to be attached to the flexible printed circuit 16 before the latter is attached to the cartridge body 10. Rework of the assembly is therefore very difficult. Furthermore, the construction is complex and costly.
U.S. Pat. No. 6,328,423 discloses a method of making an inkjet print cartridge in which a cartridge body is provided having a plurality of channels, recessed into the surface of the body, extending between a first set of terminal regions and a second set of terminal regions. The channels are filled with a conductive material to form first and second sets of electrical terminals selectively interconnected by conductive tracks, the first set of terminals being adapted for electrical connection with a printhead, and the second set of terminals being adapted for electrical connection to printer circuitry.